Fixed slash commands entered in threads displayed in main chat

[Pratheek555]

Brief Title

Acceptance Criteria fulfillment

• Preserve and forward the tmid (thread message ID) when sending slash command requests
• Ensure the Rocket.Chat server response is rendered inside the originating thread
• Prevent slash command responses from leaking into the main channel context

Fixes #1041

Video/Screenshots

PR Test Details

Note: The PR will be ready for live testing at https://rocketchat.github.io/EmbeddedChat/pulls/pr-1042 after approval. Contributors are requested to replace <pr_number> with the actual PR number.

[Spiral-Memory]

Please resolve lint issues

[Pratheek555]

Please resolve lint issues

I have resolved them :)

[Spiral-Memory]

LGTM

[Spiral-Memory]

Commands like /help are still not visible in threads, so it might be worth looking into. Lennyface is working perfectly now, thanks for the fix.

[Pratheek555]

Commands like /help are still not visible in threads, so it might be worth looking into. Lennyface is working perfectly now, thanks for the fix.

Will surely look into it!

[Pratheek555]

Hey @Spiral-Memory

Commands like /help are still not visible in threads

In the main rocketChat app when you type the /help command in threads, it shows up in the main channel itself and the same thing is happening with embedded chat too.

EmbeddedChat._.Simple.-.Simple.Storybook.Mozilla.Firefox.2026-01-16.18-39-14.mp4

Is it a issue with RocketChat itself or we keep it as intended?
I also checked most of the other commands, they seemed to work pretty fine after this current PR.

Lemme know if you want me to check anything else.

Thank you!